IR spectroscopic study of butane and propene adsorption on Pt/CeO2–Al2O3 catalysts

Abstract

IR spectra have been measured following adsorption of butane and propene on reduced Pt/CeO₂–Al₂O₃ catalysts containing 0–20% CeO₂ and also on catalysts exposed to O₂ at ambient temperature. Adsorption of butane on oxidised catalysts containing CeO₂ produced surface formate and hydrogencarbonate species on Al₂O₃ after it was heated to 350 °C, although these species were not formed in the absence of CeO₂. By contrast, adsorption of butane on reduced catalysts yielded either surface CO alone (1–5% CeO₂) or CO and carbonate ( 10% CeO₂), after heating to 350 °C. CO adsorption experiments provided evidence for Pt site deactivation after adsorption of butane. Adsorption of propene on reduced catalysts yielded adsorbed CO and either surface acrylate (Pt/Al₂O₃) or carbonate (Pt/CeO₂–Al₂O₃) on heating to 350 °C. Subsequent exposure to O₂ at ambient temperature, followed by heating to 450 °C, resulted in the desorption of all surface species. These observations are interpreted in terms of the electronic theory of catalysis and a strong Pt–CeO₂ interaction.